Obesity is a serious and growing health problem in America's youth. The prevalence of adolescent obesity, for example, increased from 11% to 13% in the past 5 years and shows no signs of abating. This increase has been accompanied by a dramatic rise in type 2 diabetes and other health complications. [unreadable] [unreadable] The goal of this renewal application is to continue efforts to improve the treatment of obese adolescents. In a study conducted during the past 36 months, we found that the addition of the weight loss medication sibutramine to a comprehensive program of diet and exercise significantly increased the induction of weight loss compared with behavioral treatment alone (7.9 kg vs. 3.4 kg, respectively). This renewal application builds on these findings by addressing two additional issues. First, we wish to show that the use of a 1200-1500 kcal/day liquid-meal replacement will induce significantly greater weight losses during the first 16 weeks of treatment than will a conventional diet of 1200-1500 kcal/day comprised of self-selected table foods with the same calorie goal. This result has been obtained in several studies of adults but has never been tested in adolescents. Second, we wish to show that long-term use of a liquid meal replacement will significantly improve the maintenance of weight loss from weeks 17-52, compared with the prescription of a conventional diet with the same calorie goal. The liquid meal replacement will facilitate the induction and maintenance of weight loss by providing participants with portion-controlled servings of a fixed calorie value. This stimulus-narrowing approach would appear to be an excellent antidote to the super-sized servings of high fat, high sugar foods found in America today. Participants in this study will be 110 teens (about 66% female), who are 13 to 17 years old, and have a body mass index (BMI) of 30 to 44 kg/m 2. [unreadable] [unreadable] The proposed study is the first randomized controlled trial to examine methods of improving the maintenance of weight loss in obese teens. We believe that the long-term use of liquid meal replacement will produce the best results obtained to date in this largely neglected population. [unreadable] [unreadable]